In the related art, an insert-replaceable grooving tool is known. When it is used, a workpiece formed of a metal material or the like is rotated around a rotation axis line and a grooving is performed by a cutting edge of a cutting insert. The insert-replaceable grooving tool performs the grooving with respect to an inner face (end face) of a machined hole which is formed about a rotation axis line of a workpiece or to an end face facing a rotation axis line direction in a step portion which is formed on an outer circumferential surface of the workpiece. For example, in the conventional insert-replaceable grooving tool 1100 shown in FIG. 23, a cutting insert 130 which is formed in a bar shape having a rectangular cross-section is detachably mounted to a tip of a tool body 11 having a shaft shape. The cutting insert 130 includes a pair of cutting edges 132 at both ends in a longitudinal direction (in left and right directions in FIG. 23 (X direction)) of the insert body 131 having a bar shape. Moreover, one cutting edge 132A which protrudes from a tip end face of the tool body 11 in the cutting edges 132 performs the grooving (an end face grooving of an inner diameter side) with respect to an inner face (end face) B of a machined hole H of a workpiece W. In the example of FIG. 23, the inner face B of the workpiece W is perpendicular to a rotation axis line WO and is formed so as to be adjacent to an inner circumferential surface (circumferential surface) S of the machined hole H. The one cutting edge 132A moves in the X direction parallel to the rotation axis line WO along the inner circumferential surface S, and therefore, performs the grooving with respect to the inner face B. Moreover, the cutting insert 130 is rotationally symmetric with respect to an insert height axis line C3 which passes through centers of the longitudinal direction and the traverse direction of the insert body 131 and extends in a height direction perpendicular to the longitudinal direction and the traverse direction. Moreover, the cutting insert 130 is formed to be planarly symmetric with respect to a virtual plane of the insert (not shown) which includes the insert height axis line C3 and is perpendicular to the longitudinal direction. The cutting insert 130 can use both cutting edges 132A and 132B regardless of whether specification of the tool body 11 is for a left hand or a right hand.
In addition, in FIG. 23, the other cutting edge 132B in the pair of cutting edges 132 is not used for cuffing, and when the one cutting edge 132A is not suitable for use due to wear, damage, or the like, the mounting direction of the insert body 131 is inverted in the longitudinal direction. Thereby, the cutting edge 132B protrudes from the tip end face of the tool body 11 and is used in the grooving.
In this way, with respect to the inner face (end face of inner diameter side) B which is disposed inside a radial direction of the inner circumferential surface S in the machined hole H of the workpiece W and faces the direction of the rotation axis line WO, the end face grooving of the inner diameter side is performed using the insert-replaceable grooving tool 1100.
Moreover, M an example of FIG. 24, the above-described cutting insert 130 is detachably mounted to the tip of the insert-replaceable grooving tool 1105 having a shaft shape. Moreover, the one cutting edge 132A which protrudes from the tip end face of the tool body 11 moves in the X direction parallel to the rotation axis line WO toward an end face E facing the direction of the rotation axis line WO in a step portion U of the workpiece W formed in a multistage cylindrical shape, and therefore, the grooving (an end face grooving of an outer diameter side) is performed with the end face E. In this example, the end face E of the workpiece W is perpendicular to the rotation axis line WO and is formed so as to be adjacent to a small diameter portion of an outer circumferential surface (circumferential surface) R. The one cutting edge 132A moves along the smaller diameter portion, and therefore, the grooving with respect to the end face E is performed.
In this way, with respect to the end face (end face of outer diameter side) E which is disposed outside a radial direction of the outer circumferential surface R in the small diameter portion of the workpiece W and faces the direction of the rotation axis line WO, the end face grooving of the outer diameter side is performed using the insert-replaceable grooving tool 1105.
Moreover, as other cutting inserts which are used in the grooving, for example, one described in PTL 1 is known.